Production process and performance of oil casing

Production process and performance of oil casing

Oil casing is used to support the well wall of oil and gas wells to ensure the normal operation of the whole well during the drilling process and after completion. According to different drilling geological conditions, several layers of casing should be used in each well. Cement cementing should be used after casing is put into the well. It is different from tubing and drill pipe, so it can not be reused and belongs to disposable consumption material. Therefore, casing consumption accounts for more than 70% of the total oil well tubing. The casing can be divided into three types according to the service conditions: casing, surface casing, technical casing and oil casing. According to the specified wall thickness, there are two kinds of welded pipe: ordinary oil casing and thickened oil casing. Different types of casing are used in the process of oil production: surface oil casing protects the drilling from shallow water and gas layers, supports wellhead equipment and maintains the weight of other layers of casing. Technical oil casing separates different layers of pressure, so as to ensure the normal circulation of drilling fluid quota and protect the production casing. In order to install anti burst device, leak proof device and liner in the well. Used to protect the well and separate the drilling mud. In the production of oil casing, the outer diameter is usually 114.3 mm to 508 mm. Different temperature control is used in different temperature section of oil casing, and heating should be carried out according to certain temperature. 27MnCrV steel AC1 = 736 ℃, AC3 = 810 ℃, tempering temperature 630 ℃ after quenching, tempering heating holding time 50min. The heating temperature is 740-810 ℃. The subcritical quenching temperature is 780 ℃ and the holding time is 15min. Because the intercritical quenching is heated in the α + γ two-phase region, the toughness can be improved while keeping the temperature.

Oil casing is the lifeline to maintain the operation of oil wells. Due to different geological conditions, the downhole stress state is complex. The comprehensive action of tensile, compressive, bending and torsional stresses on the casing body puts forward higher requirements for the quality of the casing itself. Once the casing itself is damaged due to some reason, the production of the whole well may be reduced or even scrapped. According to the strength of steel, the casing can be divided into different steel grades, namely J55, K55, N80, L80, C90, T95, P110, q125, V150, etc. Different well conditions and well depths lead to different steel grades. In corrosive environment, the casing itself is required to have corrosion resistance. In complex geological conditions, casing is also required to have anti collapse performance and anti microbial erosion. Special oil pipe is mainly used for drilling oil and gas wells and transporting oil and gas. It includes oil drilling pipe, oil casing pipe and oil extraction pipe. Oil drilling pipe is mainly used to connect drill collar and bit and transmit drilling power.

Oil casing is mainly used to support the well wall during and after well completion, so as to ensure the normal operation of the whole oil well during the drilling process and after completion. The pumping tube mainly transports oil and gas from the bottom of the oil well to the surface. Between the length of L C and the vanishing point of the thread, a defect not extending below the taper of the bottom diameter of the thread or not more than 12.5% of the specified wall thickness is allowed, but no corrosion products are allowed on the thread surface. The external chamfering (65 °) of the pipe end shall be complete on the 360 ° circumference of the pipe end. The chamfer diameter shall make the root of the thread disappear on the chamfering surface rather than on the end face of the pipe, and there shall be no edge like edge. The external chamfer of pipe end is 65 ° to 70 ° and the inner chamfer of pipe end should be 360 ° full circle chamfering, and the inner chamfer should be 40 ° to 50 ° if there is any part that has not been inverted, the chamfering should be filed manually. The casing is inserted into the borehole and fixed with cement to prevent the borehole from separating the strata and borehole collapse, and to ensure the circulation of drilling mud, so as to facilitate drilling and mining. Steel grade of oil casing: H40, J55, K55, N80, L80, C90, T95, P110, q125, V150, etc. Casing end processing form: short round thread, long round thread, partial trapezoidal thread, special thread, etc. It is mainly used to support the well wall during drilling and after completion to ensure the normal operation of the whole oil well.